Passage 2.30.6
ἐπὶ τούτου βασιλεύοντος Ἀθηνᾶν καὶ Ποσειδῶνα ἀμφισβητῆσαι λέγουσι περὶ τῆς χώρας, ἀμφισβητήσαντας δὲ ἔχειν ἐν κοινῷ· προστάξαι γὰρ οὕτω Δία σφίσι. καὶ διὰ τοῦτο Ἀθηνᾶν τε σέβουσι Πολιάδα καὶ Σθενιάδα ὀνομάζοντες τὴν αὐτὴν καὶ Ποσειδῶνα Βασιλέα ἐπίκλησιν· καὶ δὴ καὶ νόμισμα αὐτοῖς τὸ ἀρχαῖον ἐπίσημα ἔχει τρίαιναν καὶ Ἀθηνᾶς πρόσωπον.
They say that during this king's reign Athena and Poseidon disputed about the possession of the land, and after their dispute they held it in common, for such was Zeus' command. For this reason they worship Athena calling her both Polias ("Guardian of the City") and Stheniad, although she is the same goddess, and likewise Poseidon with the surname King. Indeed, the ancient coinage of the Athenians had as its emblem both a trident and the face of Athena.